Fix the quetiontype to make the deferred feedback tests pass.

question.php

@@ -345,24 +345,13 @@ class qtype_stack_question extends question_graded_automatically {
     }
 
     public function is_gradable_response(array $response) {
-        // The following code requires all *inputs* to be non-empty and valid.
-        $allblank = true;
-        foreach ($this->inputs as $name => $input) {
-            $status = $this->get_input_state($name, $response)->status;
-            if (stack_input::INVALID == $status) {
-                return false;
-            }
-            $allblank = $allblank && ($status == stack_input::BLANK);
-        }
-        return !$allblank;
-        /*
-        // I think this is closer to the mark....
-        $anyprtgradable = false;
+        // If any PRT is gradable, then we can grade the question.
         foreach ($this->prts as $index => $prt) {
-            $anyprtgradable = $anyprtgradable || $this->can_execute_prt($prt, $response);
+            if ($this->can_execute_prt($prt, $response, true)) {
+                return true;
             }
-        return $anyprtgradable;
-        */
+        }
+        return false;
     }
 
     public function get_validation_error(array $response) {
@@ -374,7 +363,7 @@ class qtype_stack_question extends question_graded_automatically {
         $fraction = 0;
 
         foreach ($this->prts as $index => $prt) {
-            $results = $this->get_prt_result($index, $response);
+            $results = $this->get_prt_result($index, $response, true);
             $fraction += $results['fraction'];
         }
         return array($fraction, question_state::graded_state_for_fraction($fraction));
@@ -384,11 +373,16 @@ class qtype_stack_question extends question_graded_automatically {
      * Do we have all the necessary inputs to execute one of the potential response trees?
      * @param stack_potentialresponse_tree $prt the tree in question.
      * @param array $response the response.
+     * @param bool $acceptvalid if this is true, then we will grade things even
+     *      if the corresponding inputs are only VALID, and not SCORE.
      * @return bool can this PRT be executed for that response.
      */
-    protected function can_execute_prt(stack_potentialresponse_tree $prt, $response) {
+    protected function can_execute_prt(stack_potentialresponse_tree $prt, $response, $acceptvalid) {
         foreach ($prt->get_required_variables(array_keys($this->inputs)) as $name) {
-            if (stack_input::SCORE != $this->get_input_state($name, $response)->status) {
+            $status = $this->get_input_state($name, $response)->status;
+            if (stack_input::SCORE == $status || ($acceptvalid && stack_input::VALID == $status)) {
+                // This input is in an OK state.
+            } else {
                 return false;
             }
         }
@@ -399,29 +393,21 @@ class qtype_stack_question extends question_graded_automatically {
      * Evaluate a PRT for a particular response.
      * @param string $index the index of the PRT to evaluate.
      * @param array $response the response to process.
+     * @param bool $acceptvalid if this is true, then we will grade things even
+     *      if the corresponding inputs are only VALID, and not SCORE.
      * @return array the result from $prt->evaluate_response(), or a fake array
      *      if the tree cannot be executed.
      */
-    public function get_prt_result($index, $response) {
+    public function get_prt_result($index, $response, $acceptvalid) {
         $this->validate_cache($response);
 
         if (array_key_exists($index, $this->prtresults)) {
             return $this->prtresults[$index];
         }
 
-        // Make sure we use modified inputs
-        $modifiedresponse = array();
-        foreach ($response as $name => $val) {
-            if (array_key_exists($name, $this->inputstates)) {
-                $modifiedresponse[$name] = $this->inputstates[$name]->contentsmodified;
-            }
-        }
-
         $prt = $this->prts[$index];
-        if ($this->can_execute_prt($prt, $response)) {
-            $this->prtresults[$index] = $prt->evaluate_response(
-                    $this->session, $this->options, $modifiedresponse, $this->seed);
-        } else {
+
+        if (!$this->can_execute_prt($prt, $response, $acceptvalid)) {
             $this->prtresults[$index] = array(
                 'feedback'   => '',
                 'answernote' => null,
@@ -431,7 +417,20 @@ class qtype_stack_question extends question_graded_automatically {
                 'penalty'    => null,
                 'fraction'   => null,
             );
+            return $this->prtresults[$index];
+        }
+
+        // Make sure we use modified inputs
+        $modifiedresponse = array();
+        foreach ($prt->get_required_variables(array_keys($this->inputs)) as $name) {
+            $state = $this->get_input_state($name, $response);
+            if (stack_input::SCORE == $state->status || ($acceptvalid && stack_input::VALID == $state->status)) {
+                $modifiedresponse[$name] = $state->contentsmodified;
             }
+        }
+
+        $this->prtresults[$index] = $prt->evaluate_response(
+                $this->session, $this->options, $modifiedresponse, $this->seed);
 
         return $this->prtresults[$index];
     }

renderer.php

@@ -55,11 +55,12 @@ class qtype_stack_renderer extends qtype_renderer {
         }
 
         foreach ($question->prts as $index => $prt) {
+            $feedback = '';
             if ($options->feedback) {
-                $result = $question->get_prt_result($index, $response);
+                $result = $question->get_prt_result($index, $response, $qa->get_state()->is_finished());
+                if (!is_null($result['valid'])) {
                     $feedback = $this->prt_feedback($index, $qa, $question, $result);
-            } else {
-                $feedback = '';
+                }
             }
             $questiontext = str_replace("[[feedback:{$index}]]", $feedback, $questiontext);
         }
@@ -101,8 +102,11 @@ class qtype_stack_renderer extends qtype_renderer {
 
         // Replace any PRT feedback.
         foreach ($question->prts as $index => $prt) {
-            $result = $question->get_prt_result($index, $response);
+            $feedback = '';
+            $result = $question->get_prt_result($index, $response, $qa->get_state()->is_finished());
+            if (!is_null($result['valid'])) {
                 $feedback = $this->prt_feedback($index, $qa, $question, $result);
+            }
             $feedbacktext = str_replace("[[feedback:{$index}]]", $feedback, $feedbacktext);
         }
 

stack/questiontest.php

@@ -85,7 +85,7 @@ class stack_question_test {
         }
 
         foreach ($this->expectedresults as $prtname => $expectedresult) {
-            $result = $question->get_prt_result($prtname, $response);
+            $result = $question->get_prt_result($prtname, $response, false);
             $results->set_prt_result($prtname, new stack_potentialresponse_tree_state(
                     '', $result['feedback'], explode(' | ', $result['answernote']),
                     $result['valid'], $result['score'], $result['penalty']));